This Park Hyatt feels like two hotels in one. The original 23-room mansion, built in 1934 by French architect Leon Dourge, defines Belle Époque elegance with elaborate ironwork, glass chandeliers, and Persian rugs.

A 2009 renovation of Buenos Aires’ Algodon Mansion, in the city’s Recoleta neighborhood, upped the ante at the six-story Belle Époque gem. The New York-based owners of Algodon (also the forces behind the Mendoza-based Algodon Wine Estates) spared no expense.